Apparatus and Methods for Fast and Accurate Biasing of Low Noise Amplifiers

This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Patent Application No. 63/649,558, filed May 20, 2024 and titled “APPARATUS AND METHODS FOR FAST AND ACCURATE BIASING OF LOW NOISE AMPLIFIERS,” which is herein incorporated by reference in its entirety.

Embodiments of the invention relate to electronic systems, and in particular, to radio frequency (RF) electronics.

A low noise amplifier (LNA) can be used to boost the amplitude of a relatively weak radio frequency (RF) signal received via an antenna. Thereafter, the boosted RF signal can be used for a variety of purposes, including, for example, driving a switch, a mixer, and/or a filter in an RF communication system.

Examples of RF communication systems with one or more LNAs include, but are not limited to, mobile phones, tablets, base stations, network access points, customer-premises equipment (CPE), laptops, and wearable electronics.

LNAs can be included in RF communication systems to amplify signals of a wide range of frequencies. For example, an LNA can be used to provide low noise amplification to RF signals in a frequency range of about 30 KHz to 300 GHz, such as in the range of about 400 MHz to about 7.125 GHz for Frequency Range 1 (FR1) of the Fifth Generation (5G) communication standard or in the range of about 24.250 GHz to about 71.000 GHz for Frequency Range 2 (FR2) of the 5G communication standard.

In certain embodiments, the present disclosure relates to a low noise amplifier. The low noise amplifier includes an amplification circuit configured to amplify a radio frequency input signal to generate a radio frequency output signal, the amplification circuit biased by a bias current and a bias voltage. The low noise amplifier further includes a biasing circuit configured to generate a sensed bias current based on sensing the bias current of the amplification circuit, the biasing circuit configured to generate the bias voltage for the amplification circuit based on comparing the sensed bias current to a reference current.

In some embodiments, the amplification circuit includes a cascode amplifier including an amplification transistor in series with a cascode transistor, the amplification transistor having an input configured to receive the radio frequency input signal.

In various embodiments, the biasing circuit includes a replica of the amplification circuit, the replica configured to conduct the sensed bias current. According to a number of embodiments, the amplification circuit includes a cascode transistor biased by a cascode bias voltage, the replica including a replica cascode transistor biased by the cascode bias voltage. In accordance with several embodiments, the biasing circuit further includes a first resistor configured to conduct the reference current, a second resistor configured to conduct the sensed bias current, and a servo amplifier having a first input coupled to the first resistor, a second input coupled to the second resistor, and an output that generates the bias voltage. According to some embodiments, the biasing circuit further includes a resistance adjustment circuit configured to modify a difference in resistance between the first resistor and the second resistor, the resistance adjustment circuit controlled based on a band control signal indicating a frequency band of the radio frequency input signal.

In several embodiments, the amplification circuit includes a common source transistor, and the bias voltage is configured to bias a gate of the common source transistor. According to various embodiments, the low noise amplifier further includes a bias resistor and a bias resistor bypass switch, the biasing circuit configured to provide the bias voltage to the gate of the common source transistor through a parallel combination of the bias resistor and the bias resistor bypass switch.

In some embodiments, the low noise amplifier further includes a controllable current source configured to generate the reference current, the controllable current source configured to control the reference current based on a gain control signal. According to a number of embodiments, the controllable current source controls a value of the reference current based on a control signal to a digital-to-analog converter.

In certain embodiments, the present disclosure relates to a mobile device. The mobile device includes an antenna and a front-end system including a low noise amplifier configured to receive a radio frequency input signal from the antenna. The low noise amplifier includes an amplification circuit configured to amplify the radio frequency input signal to generate a radio frequency output signal, and the amplification circuit is biased by a bias current and a bias voltage. The low noise amplifier further includes a biasing circuit configured to generate a sensed bias current based on sensing the bias current of the amplification circuit, and the biasing circuit is configured to generate the bias voltage for the amplification circuit based on comparing the sensed bias current to a reference current.

In some embodiments, the amplification circuit includes a cascode amplifier including an amplification transistor in series with a cascode transistor, the amplification transistor having an input configured to receive the radio frequency input signal.

In various embodiments, the biasing circuit includes a replica of the amplification circuit, the replica configured to conduct the sensed bias current. According to several embodiments, the amplification circuit includes a cascode transistor biased by a cascode bias voltage, the replica including a replica cascode transistor biased by the cascode bias voltage. In accordance with a number of embodiments, the biasing circuit further includes a first resistor configured to conduct the reference current, a second resistor configured to conduct the sensed bias current, and a servo amplifier having a first input coupled to the first resistor, a second input coupled to the second resistor, and an output that generates the bias voltage. According to some embodiments, the biasing circuit further includes a resistance adjustment circuit configured to modify a difference in resistance between the first resistor and the second resistor, the resistance adjustment circuit controlled based on a band control signal indicating a frequency band of the radio frequency input signal.

In several embodiments, the amplification circuit includes a common source transistor, and the bias voltage is configured to bias a gate of the common source transistor. According to a number of embodiments, the low noise amplifier further includes a bias resistor and a bias resistor bypass switch, the biasing circuit configured to provide the bias voltage to the gate of the common source transistor through a parallel combination of the bias resistor and the bias resistor bypass switch.

In various embodiments, the low noise amplifier further includes a controllable current source configured to generate the reference current, the controllable current source configured to control the reference current based on a gain control signal. According to some embodiments, the controllable current source controls a value of the reference current based on a control signal to a digital-to-analog converter.

In certain embodiments, the present disclosure relates to a method of radio frequency signal amplification. The method includes amplifying a radio frequency input signal using an amplification circuit of a low noise amplifier, the amplifier circuit biased by a bias current and a bias voltage. The method further includes generating a sensed bias current based on sensing the bias current of the amplification circuit using a biasing circuit, and generating the bias voltage for the amplification circuit based on comparing the sensed bias current to a reference current using the biasing circuit.

In various embodiments, the amplification circuit includes a cascode amplifier including an amplification transistor in series with a cascode transistor, the method further including receiving the radio frequency input signal at an input of the amplification transistor.

In some embodiments, the biasing circuit includes a replica of the amplification circuit, the method further including conducting the sensed current through the replica. According to a number of embodiments, the amplification circuit includes a cascode transistor biased by a cascode bias voltage, the method further including biasing a replica cascode transistor of the replica with the cascode bias voltage. In accordance with several embodiments, the biasing circuit includes a first resistor configured to conduct the reference current, a second resistor configured to conduct the sensed bias current, and a servo amplifier having a first input coupled to the first resistor, a second input coupled to the second resistor, and an output that generates the bias voltage. According to various embodiments, the biasing circuit further includes a resistance adjustment circuit configured to modify a difference in resistance between the first resistor and the second resistor, the resistance adjustment circuit controlled based on a band control signal indicating a frequency band of the radio frequency input signal.

In several embodiments, the amplification circuit includes a common source transistor, the method further including biasing a gate of the common source transistor with the bias voltage. According to a number of embodiments, the method further includes providing the bias voltage to the gate of the common source transistor through a parallel combination of a bias resistor and a bias resistor bypass switch.

In some embodiments, the method further includes generating the reference current using a controllable current source and controlling the reference current based on a gain control signal. According to various embodiments, the method further includes controlling a value of the reference current based on a control signal to a digital-to-analog converter.

The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in a multitude of different ways, for example, as defined and covered by the claims. In this description, reference is made to the drawings where like reference numerals can indicate identical or functionally similar elements. It will be understood that elements illustrated in the figures are not necessarily drawn to scale. Moreover, it will be understood that certain embodiments can include more elements than illustrated in a drawing and/or a subset of the elements illustrated in a drawing. Further, some embodiments can incorporate any suitable combination of features from two or more drawings.

The International Telecommunication Union (ITU) is a specialized agency of the United Nations (UN) responsible for global issues concerning information and communication technologies, including the shared global use of radio spectrum.

The 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications standard bodies across the world, such as the Association of Radio Industries and Businesses (ARIB), the Telecommunications Technology Committee (TTC), the China Communications Standards Association (CCSA), the Alliance for Telecommunications Industry Solutions (ATIS), the Telecommunications Technology Association (TTA), the European Telecommunications Standards Institute (ETSI), and the Telecommunications Standards Development Society, India (TSDSI).

Working within the scope of the ITU, 3GPP develops and maintains technical specifications for a variety of mobile communication technologies, including, for example, second generation (2G) technology (for instance, Global System for Mobile Communications (GSM) and Enhanced Data Rates for GSM Evolution (EDGE)), third generation (3G) technology (for instance, Universal Mobile Telecommunications System (UMTS) and High Speed Packet Access (HSPA)), and fourth generation (4G) technology (for instance, Long Term Evolution (LTE) and LTE-Advanced).

The technical specifications controlled by 3GPP can be expanded and revised by specification releases, which can span multiple years and specify a breadth of new features and evolutions.

In one example, 3GPP introduced carrier aggregation (CA) for LTE in Release 10. Although initially introduced with two downlink carriers, 3GPP expanded carrier aggregation in Release 14 to include up to five downlink carriers and up to three uplink carriers. Other examples of new features and evolutions provided by 3GPP releases include, but are not limited to, License Assisted Access (LAA), enhanced LAA (eLAA), Narrowband Internet of things (NB-IoT), Vehicle-to-Everything (V2X), and High Power User Equipment (HPUE).

3GPP introduced Phase 1 of fifth generation (5G) technology in Release 15 and introduced Phase 2 of 5G technology in Release 16. Subsequent 3GPP releases will further evolve and expand 5G technology. 5G technology is also referred to herein as 5G New Radio (NR).

5G NR supports or plans to support a variety of features, such as communications over millimeter wave spectrum, beamforming capability, high spectral efficiency waveforms, low latency communications, multiple radio numerology, and/or non-orthogonal multiple access (NOMA). Although such RF functionalities offer flexibility to networks and enhance user data rates, supporting such features can pose a number of technical challenges.

The teachings herein are applicable to a wide variety of communication systems, including, but not limited to, communication systems using advanced cellular technologies, such as LTE-Advanced, LTE-Advanced Pro, and/or 5G NR.

is a schematic diagram of one example of a communication network. The communication networkincludes a macro cell base station, a small cell base station, and various examples of user equipment (UE), including a first mobile device, a wireless-connected car, a laptop, a stationary wireless device, a wireless-connected train, a second mobile device, and a third mobile device

Although specific examples of base stations and user equipment are illustrated in, a communication network can include base stations and user equipment of a wide variety of types and/or numbers.

For instance, in the example shown, the communication networkincludes the macro cell base stationand the small cell base station. The small cell base stationcan operate with relatively lower power, shorter range, and/or with fewer concurrent users relative to the macro cell base station. The small cell base stationcan also be referred to as a femtocell, a picocell, or a microcell. Although the communication networkis illustrated as including two base stations, the communication networkcan be implemented to include more or fewer base stations and/or base stations of other types.

Although various examples of user equipment are shown, the teachings herein are applicable to a wide variety of user equipment, including, but not limited to, mobile phones, tablets, laptops, IoT devices, wearable electronics, customer premises equipment (CPE), wireless-connected vehicles, wireless relays, and/or a wide variety of other communication devices. Furthermore, user equipment includes not only currently available communication devices that operate in a cellular network, but also subsequently developed communication devices that will be readily implementable with the inventive systems, processes, methods, and devices as described and claimed herein.

The illustrated communication networkofsupports communications using a variety of cellular technologies, including, for example, 4G LTE and 5G NR. In certain implementations, the communication networkis further adapted to provide a wireless local area network (WLAN), such as WiFi. Although various examples of communication technologies have been provided, the communication networkcan be adapted to support a wide variety of communication technologies.

Various communication links of the communication networkhave been depicted in. The communication links can be duplexed in a wide variety of ways, including, for example, using frequency-division duplexing (FDD) and/or time-division duplexing (TDD). FDD is a type of radio frequency communications that uses different frequencies for transmitting and receiving signals. FDD can provide a number of advantages, such as high data rates and low latency. In contrast, TDD is a type of radio frequency communications that uses about the same frequency for transmitting and receiving signals, and in which transmit and receive communications are switched in time. TDD can provide a number of advantages, such as efficient use of spectrum and variable allocation of throughput between transmit and receive directions.

In certain implementations, user equipment can communicate with a base station using one or more of 4G LTE, 5G NR, and WiFi technologies. In certain implementations, enhanced license assisted access (eLAA) is used to aggregate one or more licensed frequency carriers (for instance, licensed 4G LTE and/or 5G NR frequencies), with one or more unlicensed carriers (for instance, unlicensed WiFi frequencies).

As shown in, the communication links include not only communication links between UE and base stations, but also UE to UE communications and base station to base station communications. For example, the communication networkcan be implemented to support self-fronthaul and/or self-backhaul (for instance, as between mobile deviceand mobile device).

The communication links can operate over a wide variety of frequencies. In certain implementations, communications are supported using 5G NR technology over one or more frequency bands that are less than 6 Gigahertz (GHz) and/or over one or more frequency bands that are greater than 6 GHz. For example, the communication links can serve Frequency Range 1 (FR1), Frequency Range 2 (FR2), or a combination thereof. In one embodiment, one or more of the mobile devices support a HPUE power class specification.

In certain implementations, a base station and/or user equipment communicates using beamforming. For example, beamforming can be used to focus signal strength to overcome path losses, such as high loss associated with communicating over high signal frequencies. In certain embodiments, user equipment, such as one or more mobile phones, communicate using beamforming on millimeter wave frequency bands in the range of 30 GHz to 300 GHz and/or upper centimeter wave frequencies in the range of 6 GHz to 30 GHz, or more particularly, 24 GHz to 30 GHz. Cellular user equipment can communicate using beamforming and/or other techniques over a wide range of frequencies, including, for example, FR2-1 (24 GHz to 52 GHz), FR2-2 (52 GHz to 71 GHz), and/or FR1 (400 MHz to 7125 MHz).

Different users of the communication networkcan share available network resources, such as available frequency spectrum, in a wide variety of ways.

In one example, frequency division multiple access (FDMA) is used to divide a frequency band into multiple frequency carriers. Additionally, one or more carriers are allocated to a particular user. Examples of FDMA include, but are not limited to, single carrier FDMA (SC-FDMA) and orthogonal FDMA (OFDMA). OFDMA is a multicarrier technology that subdivides the available bandwidth into multiple mutually orthogonal narrowband subcarriers, which can be separately assigned to different users.

Other examples of shared access include, but are not limited to, time division multiple access (TDM A) in which a user is allocated particular time slots for using a frequency resource, code division multiple access (CDMA) in which a frequency resource is shared amongst different users by assigning each user a unique code, space-divisional multiple access (SDMA) in which beamforming is used to provide shared access by spatial division, and non-orthogonal multiple access (NOM A) in which the power domain is used for multiple access. For example, NOMA can be used to serve multiple users at the same frequency, time, and/or code, but with different power levels.

Enhanced mobile broadband (eMBB) refers to technology for growing system capacity of LTE networks. For example, eMBB can refer to communications with a peak data rate of at least 10 Gbps and a minimum of 100M bps for each user. Ultra-reliable low latency communications (uRLLC) refers to technology for communication with very low latency, for instance, less than 2 milliseconds. uRLLC can be used for mission-critical communications such as for autonomous driving and/or remote surgery applications. Massive machine-type communications (mMTC) refers to low cost and low data rate communications associated with wireless connections to everyday objects, such as those associated with Internet of Things (IoT) applications.

The communication networkofcan be used to support a wide variety of advanced communication features, including, but not limited to, eMBB, uRLLC, and/or mMTC.

is a schematic diagram of one example of a communication link using carrier aggregation. Carrier aggregation can be used to widen bandwidth of the communication link by supporting communications over multiple frequency carriers, thereby increasing user data rates and enhancing network capacity by utilizing fragmented spectrum allocations.

In the illustrated example, the communication link is provided between a base stationand a mobile device. As shown in, the communications link includes a downlink channel used for RF communications from the base stationto the mobile device, and an uplink channel used for RF communications from the mobile deviceto the base station.

Althoughillustrates carrier aggregation in the context of FDD communications, carrier aggregation can also be used for TDD communications.

In certain implementations, a communication link can provide asymmetrical data rates for a downlink channel and an uplink channel. For example, a communication link can be used to support a relatively high downlink data rate to enable high speed streaming of multimedia content to a mobile device, while providing a relatively slower data rate for uploading data from the mobile device to the cloud.

In the illustrated example, the base stationand the mobile devicecommunicate via carrier aggregation, which can be used to selectively increase bandwidth of the communication link. Carrier aggregation includes contiguous aggregation, in which contiguous carriers within the same operating frequency band are aggregated. Carrier aggregation can also be non-contiguous, and can include carriers separated in frequency within a common band or in different bands.

In the example shown in, the uplink channel includes three aggregated component carriers f, f, and f. Additionally, the downlink channel includes five aggregated component carriers f, f, f, f, and f. Although one example of component carrier aggregation is shown, more or fewer carriers can be aggregated for uplink and/or downlink. Moreover, a number of aggregated carriers can be varied over time to achieve desired uplink and downlink data rates.